1 Erratum to: Exp Fluids (2015) 56:112 DOI 10.1007/s00348-015-1982-y

In the original publication of the article, a term is missing in Eq. 5. The correct version of Eq. 5 is

$$ \tau_{1} \frac{dX}{dt} + X = X_{0} (\alpha_{s} ) + X_{0}^{'} (\alpha_{s} ) \cdot (u - \tau_{2} \dot{u}) $$
(5)